The present invention relates generally to treatment of obesity, and specifically to invasive techniques and apparatus for treating obesity.
Invasive treatments for obesity are often recommended for patients with a body mass index (mass/height2 [kg/m2]) which is greater than 35 or 40. For such patients, their weight is commonly associated with increased risk of heart disease, diabetes, and arthritis. Preferably, the invasive treatments are accompanied by changes in lifestyle, such as improved eating habits and an appropriate exercise regimen.
U.S. Pat. No. 6,067,991 to Forsell, U.S. Pat. No. 5,601,604 to Vincent, and U.S. Pat. No. 5,234,454 to Bangs, and U.S. Pat. Nos. 5,449,368, 5,226,429 and 5,074,868 to Kuzmak, which are incorporated herein by reference, describe mechanical instruments for implantation in or around the stomach of an obese patient.
U.S. Pat. No. 5,690,691 to Chen et al., which is incorporated herein by reference, describes a gastric pacemaker for treating obesity and other conditions. The pacemaker includes multiple electrodes which are placed at various positions on the gastrointestinal (GI) tract, and which deliver phased electrical stimulation to pace peristaltic movement of material through the GI tract.
U.S. Pat. No. 5,423,872 to Cigaina, which is incorporated herein by reference, describes apparatus for applying electrical pulses to the distal gastric antrum of a patient, so as to reduce the motility of the stomach and to thereby treat obesity or another condition.
U.S. Pat. Nos. 5,188,104 and 5,263,480 to Wernicke et al., which are incorporated herein by reference, describe a method for stimulating the vagus nerve of a patient so as to alleviate an eating disorder.
U.S. Pat. Nos. 6,104,955, 6,091,992, and 5,836,994 to Bourgeois, U.S. Pat. No. 6,026,326 to Bardy, and U.S. Pat. No. 3,411,507 to Wingrove, which are incorporated herein by reference, describe the application of electrical signals to the GI tract to treat various physiological disorders.
PCT Patent Publication WO 99/03533 to Ben-Haim et al., entitled, xe2x80x9cSmooth muscle controller,xe2x80x9d and U.S. patent application Ser. No. 09/481,253 in the national phase thereof, both of which are assigned to the assignee of the present patent application and are incorporated herein by reference, describe apparatus and methods for applying signals to smooth muscle so as to modify the behavior thereof. In particular, apparatus for controlling the stomach is described in which a controller applies an electrical field to electrodes on the stomach wall so as to modify the reaction of muscle tissue therein to an activation signal, while not generating a propagating action potential in the tissue. In the context of the present patent application and in the claims, the use of such a non-excitatory signal to modify the response of one or more cells to electrical activation thereof, without inducing action potentials in the cells, is referred to as Excitable-Tissue Control (ETC). Use of an ETC signal is described with respect to treating obesity, by applying the ETC signal to the stomach so as to delay or prevent emptying of the stomach. In addition, a method is described for increasing the motility of the gastrointestinal tract, by applying an ETC signal to a portion of the tract in order to increase the contraction force generated in the portion.
PCT Patent Publication WO 97/25098, to Ben-Haim et al., entitled xe2x80x9cElectrical muscle controller,xe2x80x9d and the corresponding U.S. patent application Ser. No. 09/101,723, which are assigned to the assignee of the present patent application and are incorporated herein by reference, describe methods for modifying the force of contraction of a heart chamber by applying an ETC signal to the heart.
It is an object of some aspects of the present invention to provide improved apparatus and methods for treatment of medical conditions which relate to the gastrointestinal tract.
It is a further object of some aspects of the present invention to provide improved apparatus and methods for treating obesity.
In preferred embodiments of the present invention, apparatus for treating a condition such as obesity comprises a set of one or more electrodes which are applied to one or more sites of the gastrointestinal (GI) tract of a patient. A control unit preferably drives the electrode set to apply an Excitable-Tissue Control (ETC) signal to the GI tract, so as to modulate contraction of muscles of the gastrointestinal tract and to thereby treat the condition.
In a preferred embodiment, the electrodes are applied to the stomach, and the control unit drives the electrodes to apply an enhancement signal which includes, as appropriate, the ETC signal and/or an excitatory signal. Thus, the enhancement signal may induce contractions and/or increase or otherwise modify the contraction forces generated by muscles of the stomach.
For some applications, the enhancement signal is applied so as to modify a contraction pattern of some of the stomach""s muscles, in order to reduce the cross-sectional area of a portion of the stomach. The narrow ring thereby generated reduces the volume of a region of the stomach, and increases the sensation of satiety felt by the patient compared to that which would be felt without the application of this embodiment of the invention. For example, the enhancement signal may cause an xe2x80x9cindentingxe2x80x9d of the stomach wall, whereby food is limited in its ability to vacate the esophageal region of the stomach. Consequently, this portion of the stomach is stretched more than usual for the volume of food ingested, and an earlier sensation of satiety is induced. This embodiment thus employs electrical signals to cause a narrowing of the stomach analogous to that produced mechanically by the gastric bands described in the Background section of the present patent application. Unlike these prior art mechanical bands, however, this application of the present invention allows the extent of the narrowing to be moderated in real time by the control unit without mechanical intermediaries (e.g., modulation of fluid pressure).
Alternatively or additionally, the enhancement signal is applied, prior to and/or during a meal, so as to reduce the overall size of the stomach, thereby increasing the tension in the wall of the stomach when food is in the stomach. This increased tension typically yields a corresponding increase in the patient""s sensation of satiety, and thus substantially reduces the likelihood of the patient overeating.
Further alternatively or additionally, repeated application of the enhancement signal engenders a long-term shortening of muscle fibers of the stomach, and, consequently, a reduction of the size of the stomach, even at times when the signal is not being applied. Thus, for example, the enhancement signal may be applied, intermittently throughout the day, over a period of days, weeks, or months, so as to induce desired structural changes in the stomach which last, preferably, for at least several days or weeks after removal of the signal. Advantageously, due to the stomach""s reduced size, it is typically stretched during and after a meal to a greater extent than would occur without application of the enhancement signal, and thus greater sensations of satiety are felt by the patient. Optionally, the signal may be applied when the patient""s stomach is expected to be relatively empty (e.g., each morning for one hour prior to the patient waking up), so as to maximize the extent to which the muscle fibers are able to shorten in response to the signal.
For some patients, it is desirable to apply the enhancement signal according to a schedule, whereby constriction of the stomach induces a feeling of satiety at times when the patient might choose to eat but should not be eating. At other times, e.g., when the patient is sleeping, the signal is typically not applied. Alternatively or additionally, the enhancement signal is (a) applied during one or more meals during the day, so as to reduce the patient""s appetite during those meals, and (b) removed during meals eaten during the remainder of the day, so as to prevent nutritional deficiencies which might occur in some patients from any inappropriate, excessive use of the signals described herein.
In a preferred embodiment, the enhancement signal is applied to muscle in one portion of the stomach, so as to induce and/or modify a contraction of the stimulated muscle which, in turn, causes stretching of stretch-receptors in an adjacent portion of the stomach. This form of contraction-mediated stretching simulates the normal satiety signaling of the stomach""s stretch-receptors, without the patient having eaten the quantities of food which would normally be required to trigger this satiety response.
Alternatively or additionally, some or all of the electrodes are placed in a vicinity of the pyloric sphincter, and the control unit drives the electrode set to apply the enhancement signal so as to increase a contraction force of the sphincter. The increased force typically reduces the sphincter""s cross-section, and thereby generally extends a period of time in which partially-digested food remains in the stomach.
In a preferred embodiment, one or more electrodes are applied to or in a vicinity of respective sites of the arterial supply of the patient""s small intestine. Typically, the control unit drives some or all of the electrodes to apply signals which cause a controllable level of constriction of the arteries to which these electrodes are coupled. The constriction produced thereby preferably transiently and controllably reduces the blood flow to the small intestine, and, it is believed, thereby reduces the total number of calories which are ultimately absorbed into the patient""s bloodstream during and after eating a meal.
There is therefore provided, in accordance with a preferred embodiment of the present invention, apparatus for treating a condition, including:
a set of one or more electrodes, adapted to be applied to one or more respective sites in a vicinity of a stomach of a patient; and
a control unit, adapted to drive the electrode set to apply an Excitable-Tissue Control (ETC) signal to the sites, configured such that application thereof decreases a cross-sectional area of at least a portion of the stomach.
Preferably, the set of one or more electrodes includes a first set of one or more electrodes, and the apparatus includes a second set of one or more electrodes, adapted to be applied to one or more respective sites in a vicinity of a pyloric sphincter of the stomach. The control unit is preferably adapted to drive the second electrode set to apply an ETC signal configured such that application thereof increases a contraction force of the sphincter and extends a period of time in which partially-digested food remains in the stomach.
Further preferably, the control unit is adapted to configure the ETC signal such that application thereof decreases the cross-sectional area of the portion of the stomach by at least 20%, for a substantially continuous period greater than about one minute.
Still further preferably, the portion of the stomach includes a first portion of the stomach, and the control unit is adapted to configure the ETC signal such that ingestion of food by the patient in conjunction with application of the ETC signal to the first portion induces stretching of a stretch-receptor in a second portion of the stomach that induces a sensation of satiety.
In a preferred embodiment, the control unit is adapted to drive the electrode set to apply the signal over a sufficient time period so as to engender a long-term structural change of the stomach.
Typically, the electrode set is adapted to be applied in contact with muscle tissue of the stomach.
The control unit is preferably adapted to configure the ETC signal such that the decreased cross-sectional area impedes passage of ingesta through the stomach.
Alternatively or additionally, the control unit is adapted to configure the ETC signal such that application thereof decreases a volume of the stomach.
In some preferred embodiments of the present invention, the control unit is adapted to configure a timing parameter of the ETC signal responsive to timing of natural gastric electrical activity. The ETC signal is typically applied as a series of biphasic pulses. Preferably, the control unit is adapted to configure the ETC signal to have a duration of at least about 1 second. Further preferably, the duration is at least about 3 seconds.
For some applications, the apparatus includes at least one stimulating electrode, and the control unit is adapted to drive the stimulating electrode to apply an excitatory signal to muscle tissue of the stomach in conjunction with driving the electrode set to apply the ETC signal. In these cases, the control unit is typically adapted to drive the stimulating electrode to apply gastric pacing pulses to the stomach.
Preferably, the control unit is adapted to receive a patient signal, input by the patient, and to drive and withhold driving the electrode set responsive to the patient signal.
The control unit is typically adapted to drive the electrode set in accordance with a schedule programmed into the control unit. For example, the control unit may be adapted to drive the electrode set during at least one meal eaten by the patient during a 24 hour period, and to withhold driving the electrode set during another meal eaten by the patient during the 24 hour period. Alternatively or additionally, the control unit is adapted to withhold driving the electrode set during time periods designated as times when the patient generally does not eat.
For some applications, the control unit is adapted to drive at least one of the electrodes to apply an excitatory pulse in conjunction with the ETC signal. Preferably, the control unit is adapted to drive the at least one electrode to apply the excitatory pulse as a biphasic pulse. Alternatively or additionally, the control unit is adapted to drive the at least one electrode to initiate applying the ETC signal at least about 100 ms following a termination of the excitatory pulse. Preferably, the control unit is adapted to drive the at least one electrode to initiate applying the ETC signal less than about 1000 ms following a termination of the excitatory pulse.
Preferably, the control unit is adapted to drive the electrode set while the patient is eating. The control unit may, for example, be adapted to receive a patient signal, input by the patient, indicative of the patient eating. In this case, the control unit is preferably adapted to receive by way of the patient signal an indication of a nutritional quality of food being eaten by the patient and to configure a parameter of the ETC signal responsive to the patient signal.
Alternatively or additionally, the apparatus includes a sensor which is adapted to convey to the control unit a signal responsive to the patient eating. As appropriate, the sensor may include a blood sugar sensor or a mechanical sensor. Alternatively or additionally, the sensor includes a sensing electrode, adapted to be coupled in a vicinity of a gastrointestinal tract of the patient. For some applications, the sensing electrode includes one of the one or more electrodes.
Preferably, the sensor is adapted to convey the signal responsive to a quantity of food ingested by the patient, and the control unit is adapted to withhold driving the electrode set, as appropriate, responsive to the quantity (e.g., if the quantity is less than a threshold quantity).
In a preferred embodiment, the control unit is adapted to configure the ETC signal such that application thereof decreases the cross-sectional area of a region of the stomach, and maintains the decreased cross-sectional area in the region for a duration greater than about 10 seconds.
In a preferred embodiment, the control unit is adapted to configure the ETC signal such that application thereof increases intra-gastric pressure, thereby inducing a sensation of satiety.
For some applications, the apparatus includes a second set of one or more electrodes, adapted to be applied to one or more respective sites in a vicinity of the lower-esophageal sphincter. The control unit is preferably adapted to drive the second electrode set to apply a signal to the sphincter, configured such that application thereof increases a contraction force generated by the sphincter.
There is further provided, in accordance with a preferred embodiment of the present invention, apparatus for treating a condition, including:
a set of one or more electrodes, adapted to be applied to one or more respective sites in a vicinity of a pyloric sphincter of a stomach of a patient; and
a control unit, adapted to drive the electrode set to apply an Excitable-Tissue Control (ETC) signal to the sites, configured such that application thereof increases a contraction force of the sphincter and extends a period of time in which partially-digested food remains in the stomach.
Preferably, the control unit is adapted to configure the ETC signal such that driving the electrode set to apply the ETC signal increases the contraction force for a substantially continuous period greater than about 1 minute.
As appropriate, the electrode set may be adapted to be applied in contact with muscle tissue of an antral portion of the stomach and/or in contact with muscle tissue of the sphincter.
There is still further provided, in accordance with a preferred embodiment of the present invention, apparatus for treating a condition, including:
a set of one or more electrodes, adapted to be applied to one or more respective sites in a vicinity of a body of a stomach of a patient; and
a control unit, adapted to drive the electrode set to apply to the body of the stomach a signal configured such that application thereof increases a level of contraction of muscle tissue of the body of the stomach, and decreases a cross-sectional area of a portion of the body of the stomach for a substantially continuous period greater than about 3 seconds.
Preferably, the control unit is adapted to configure the signal such that application thereof decreases the cross-sectional area of the portion or a substantially continuous period greater than about 10 seconds.
There is yet further provided, in accordance with a preferred embodiment of the present invention, apparatus for treating a condition, including:
a set of one or more electrodes, adapted to be applied to one or more respective sites in a vicinity of a first portion of a stomach of a patient; and
a control unit, adapted to drive the electrode set to apply to the portion of the stomach a signal configured such that application thereof increases a level of contraction of muscle tissue of the portion, and configured such that ingestion of food by the patient in conjunction with application of the signal induces stretching of a stretch-receptor in a second portion of the stomach.
Preferably, the control unit is adapted to drive the electrode set to apply the signal to a body of the stomach, and to configure a parameter of the signal such that the increased level of contraction of the muscle tissue impedes passage of ingesta through the stomach and increases a level of tension in a fundic wall of the stomach.
There is also provided, in accordance with a preferred embodiment of the present invention, apparatus for treating a condition, including:
a set of one or more electrodes, adapted to be applied to one or more respective sites on an arterial supply of small intestine of a patient; and
a control unit, adapted to drive the electrode set to apply a signal to the sites, configured such that application thereof induces constriction of one or more arteries in the arterial supply and decreases a quantity of digestion products which are absorbed into blood of the patient from the small intestine.
Preferably, the control unit is adapted to determine an approximate time of initiation of eating, and to initiate driving the electrode set to apply the signal at least ten minutes subsequent thereto. Typically, the control unit is adapted to determine the approximate time of initiation of eating responsive to receiving a patient signal, input by the patient.
In a preferred embodiment, the apparatus includes a sensor which is adapted to convey to the control unit a signal indicative of food being in a gastrointestinal tract of the patient.
There is additionally provided, in accordance with a preferred embodiment of the present invention, apparatus for treating a condition, including:
a set of one or more electrodes, adapted to be applied to one or more respective sites of a stomach of a patient; and
a control unit, adapted to drive the electrode set to apply to the stomach, over a sufficient time period, a sequence of pulses configured so as to engender a long-term structural change of the stomach.
Preferably, the control unit is adapted to configure the sequence of pulses as an Excitatory-Tissue Control (ETC) signal. Alternatively or additionally, the control unit is adapted to configure a parameter of the sequence of pulses such that the application of the pulses over the time period is such as to engender a continuation of the structural change for at least two days following a termination of the application of the pulses.
Preferably, the control unit is adapted to configure a parameter of the sequence of pulses such that the application of the pulses over the time period is such as to reduce a characteristic length of muscle fibers of the stomach. Alternatively or additionally, the control unit is adapted to configure a parameter of the sequence of pulses such that the application of the pulses over the time period is such as to reduce a characteristic size of the stomach.
For some applications, the control unit is adapted to drive the electrode set to apply the pulses for at least two days. Preferably, the control unit is adapted to drive the electrode set to apply the pulses for at least two weeks.
In a preferred embodiment, the control unit is adapted to drive the electrode set in accordance with a schedule programmed into the control unit. For example, the control unit may be adapted to drive the electrode set at times when the patient""s stomach is generally empty, or during a meal eaten by the patient.
There is yet additionally provided, in accordance with a preferred embodiment of the present invention, a method for treating a condition, including:
applying an Excitable-Tissue Control (ETC) signal to one or more sites in a vicinity of a stomach of a patient; and
configuring the ETC signal such that application thereof to the one or more sites decreases a cross-sectional area of at least a portion of the stomach.
There is still additionally provided, in accordance with a preferred embodiment of the present invention, a method for treating a condition, including:
applying an Excitable-Tissue Control (ETC) signal to one or more sites in a vicinity of a pyloric sphincter of a stomach of a patient; and
configuring the ETC signal such that application thereof to the one or more sites increases a contraction force of the sphincter and extends a period of time in which partially-digested food remains in the stomach.
There is also provided, in accordance with a preferred embodiment of the present invention, a method for treating a condition, including:
applying a signal to one or more sites in a vicinity of a body of a stomach of a patient; and
configuring the signal such that application thereof to the one or more sites increases a level of contraction of muscle tissue of a portion of the body of the stomach, and decreases a cross-sectional area of the portion for a substantially continuous period greater than about 3 seconds.
There is further provided, in accordance with a preferred embodiment of the present invention, a method for treating a condition, including:
applying a signal to one or more sites in a vicinity of a first portion of a stomach of a patient; and
configuring the signal such that the application thereof increases a level of contraction of muscle tissue of the portion and stretches a stretch-receptor in a second portion of the stomach.
There is still further provided, in accordance with a preferred embodiment of the present invention, a method for treating a condition, including:
applying a signal to one or more sites on an arterial supply of small intestine of a patient; and
configuring the signal such that application thereof to the sites induces constriction of one or more arteries in the arterial supply and decreases a quantity of digestion products which are absorbed into blood of the patient from the small intestine.
There is yet further provided, in accordance with a preferred embodiment of the present invention, a method for treating a condition, including:
applying a sequence of pulses over a time period to one or more sites of a stomach of a patient; and
configuring the sequence of pulses such that application thereof to the one or more sites engenders a long-term structural change of the stomach.
The present invention will be more fully understood from the following detailed description of the preferred embodiments thereof, taken together with the drawings, in which: